Glass-ceramics made from arc-melting slag of waste incineration fly ash

Grate fly ash and fluidized bed fly ash mixed with glass cullet additive respectively were melted in the electronic arc-furnace. The product, arc-melting slag, was further treated by crushing, pressing and heat treatment in order to make the glass-ceramics. The crystallization behaviors of the produced glass-ceramics were examined by differential thermal analysis (DTA), X-ray diffractometry (XRD) and scanning electron microscopy (SEM). Results show that main crystalline phase of the glass-ceramics from grate fly ash is wollastonite (CaSiO₃) with small amount of diopside (Ca(Mg,Al)(Si,Al)₂O₆), and that from fluidized bed fly ash is diopside (Ca(Mg,Al)(Si,Al)₂O₆). It is found that the glass-ceramics sintered at 850 °C and 1 000 °C from grate fly ash and fluidized bed fly ash respectively have the optimal physical, mechanical and chemical characteristics. Glass-ceramics samples, produced from incinerator fly ash with desirable properties and the low leaching concentration of heavy metals, can be the substitute of nature materials such as marble, granite and porcelain tiles.     

Influence of fly ash fineness and shape on the porosity and permeability of blended cement pastes

The effects of the fineness and shape of fly ash on the porosity and air permeability of cement pastes were investigated. Pulverized coal combustion (PCC) fly ash and fluidized bed coal combustion (FBC) fly ash classified into three different finenesses were used. River sand with particle size distribution similar to that of fly ash was also used for comparison. Portland cement was replaced with fly ash and ground sand at the dosages of 0, 20wt%, and 40wt%. A water-to-binder ratio (w/b) of 0.35 was used thr...     

循环流化床锅炉灰渣对混凝土强度的影响

以利废为目的,进行循环流化床锅炉灰渣对混凝土强度影响的研究.结果表明：单掺循环流化床锅炉炉渣对混凝土强度不利,且间接冷却炉渣对混凝土强度的影响小于直接冷却炉渣;双掺循环流化床锅炉灰渣可使混凝土强度得以改善,且随循环流化床锅炉灰渣掺量的增加,混凝土的强度总体仍呈下降趋势,掺量在25%以内变化的灰渣对混凝土抗折强度的影响明显小于对抗压强度的影响.     

生活垃圾焚烧飞灰重金属特性分析

对国内四个不同的垃圾焚烧厂产生的飞灰进行物理及化学特性分析.四种飞灰在颗粒尺寸分布上有相似的规律,飞灰中重金属的质量分数分析结果表明采用纯垃圾焚烧的炉排炉飞灰中的质量分数高于掺煤混烧的流化床焚烧飞灰中的质量分数.随着飞灰颗粒尺寸的减小,飞灰中重金属的浓度呈现增加的趋势.飞灰的渗滤特性表明,飞灰中Ca质量分数越高,飞灰的酸中合能力越强,且重金属的渗出率受飞灰渗滤液的pH影响大,而在碱性渗滤条件下受飞灰中重金属质量分数的影响小.     

Mechanism of flue gas simultaneous desulfurization and denitrification using the highly reactive absorbent

Using slurry mixed by fly ash and alkaline material, removal of SO2 in industrial waste gas had been reported in the 1970s, which was named the wet scrubbing[1]. Sincethen, there have been many reports about flue gas desulfurization using the reactive ab- sorbent prepared with flying ash. There are four kinds as follows: (1) Using slurry of fly ash as absorbent[2―4], which mainly utilize the property of fly ash for desulphurization, but the removal efficiency is not high. (2) Using fly ash a…     

流化床燃烧中煤含灰量对灰渣形成特性的影响

为了研究煤颗粒灰质量分数对煤在流化床燃烧过程中灰渣形成特性的影响,在一台小型流化床反应炉上进行煤的灰质量分数对灰渣形成特性的实验.按煤颗粒的灰质量分数,把义马烟煤分为6个颗粒组,并选用各颗粒组的3个粒径范围的煤颗粒进行燃烧实验,研究煤颗粒的灰质量分数对底渣质量分数、底渣与飞灰中的碳量质量分数和粒径分布的影响.结果表明,随着煤颗粒灰质量分数的增加,燃烧形成的底渣质量分数增加,而煤颗粒的燃尽率和飞灰中的碳质量分数都降低.在粒径和燃烧时间相同的条件下,随着颗粒灰质量分数的增加,底渣中留在本粒径档的颗粒质量分数明显增加,而细颗粒的质量分数明显减少.而颗粒灰质量分数对飞灰的粒径分布没有明显的影响.     

Shell煤气化飞灰粘附特性影响因素探讨

针对Shell粉煤气化炉飞灰的粘附特性,利用XRF、激光粒度分析仪、SEM-EDX等仪器对采自皖北、云南矿区的两种煤在Shell气化过程中形成的飞灰样品进行了分析检测,探讨了化学成分、粒度分布、表面形貌及元素组成等因素对飞灰粘附特性的影响。结果表明,皖北煤飞灰中一些微量元素含量比云南煤飞灰含量高,颗粒直径在1-2μm范围的大颗粒数明显少于云南煤飞灰,但是飞灰的比表面积大于云南煤飞灰,这是皖北煤飞灰的粘附性比云南煤要高的主要原因;此外,飞灰颗粒为球状,表面附着小的球形颗粒,该颗粒的Ca元素含量较高,使得它们彼此容易粘连在一起,从而促进了飞灰的粘附和沉积。     

多管流化罐返料器的冷态模型实验研究

为满足循环床沸腾炉飞灰复燃系统的需要,本文提出了一种新型飞灰返料器—多管流化罐返料器.与传统的飞灰返料器不同,该设备有数根输灰管平行工作.借助于相似理论,笔者建立了多管流化罐试验台,并对其性能进行了实验研究.结果表明.新设备作为飞灰复燃系统的返料器具有显著的优越性.     

掺固硫灰干粉砂浆的性能研究

对掺固硫灰干粉砂浆的性能进行了研究。讨论了固硫灰细度、掺量及与粉煤灰复掺对干粉砂浆工作性能、力学性能和膨胀性的影响。结果表明：经预处理固硫灰可以应用于干粉砂浆中,且掺量为10%时效果最佳。固硫灰与粉煤灰等矿物掺合料复掺可以改善干粉砂浆性能。     

Physicochemical properties and heavy metals leachability of fly ash from coal-fired power plant

The physicochemical properties of fly ash from two kinds of coal-fired power plants were studied. Three aspects were examined: the micro-morphology, the mineral composition and the content of heavy metals. The results show that the fly ash from plants using a circulating fluidized bed are more irregular particles, while the particles from the plants using a pulverized coal-fired boiler are mainly spherical in shape. Quartz and mullite are the main crystalline phases in the ash. Clearly, both the technology and the coal used by a power plant can influence the mineral composition of the ash. The mineral composition of fly ash from a circulating fluidized bed is more complex than that from a pulverized coal-fired boiler. The quantity of elements found in the fly ash is greater than that found in the bottom ash for the same plant. Heavy metals are likely to be enriched in the fly ash. Heavy metal leachability was studied using two leaching methods. The results indicate that most of the heavy metals that leached during either batch leaching or column leaching experiments did not exceed the related maximum concentration standards. But Ni concentrations in the leachates from both batch and column tests exceed the standard. The highest excess rates in both tests were 572% and 497%, which levels might threaten the environment.     

Microstructures and thermal properties of municipal solid waste incineration fly ash

To analyze the feasibility of utilization of thermal technology in fly ash treatment, thermal properties and microstructures of municipal solid waste incineration (MSWI) fly ash were studied by measuring the chemical element composition, specific surface area, pore sizes, functional groups, TEM image, mineralogy and DSC-TG curves of raw and sintered fly ash specimens. The results show that MSWI fly ash particles mostly have irregular shapes and non-typical pore structure, and the supersonic treatment improves the pore structure; MSWI fly ash consists of such crystals as SiO₂, CaSO₄ and silica-aluminates, and some soluble salts like KCl and NaCl. During the sintering process, mineralogy changes largely and novel solid solutions are produced gradually with the rise of temperature. Therefore, the utilization of a proper thermal technology not only destructs those persistent organic toxicants but also stabilizes hazardous heavy metals in MSWI fly ash.     

煤灰助熔剂对灰熔点影响的研究

采用ＣａＯ，Ｆｅ２Ｏ３以及石灰石、硫酸渣助熔剂按不同比例与煤灰混合，对助熔剂对煤灰熔点的影响进行试验研究．结果表明，在还原性气氛下，添加适量ＣａＯ和Ｆｅ２Ｏ３可使煤灰熔点下降，当ＣａＯ添加率超过４０％时反使灰熔点急剧上升；石灰石、硫酸渣中起助熔作用的成分是其中的ＣａＯ和Ｆｅ２Ｏ３，其助熔行为与分析纯ＣａＯ和Ｆｅ２Ｏ３基本一致．     

The Cement Solidification of Municipal Solid Waste Incineration Fly Ash

The chemical composition, the content and the leachability of heavy metals in municipal solid waste incineration （ MSWI） fly ash were tested and analyzed. It is shown that the leachability of Pb and Cr exceeds the leaching toxicity standard, and so the MSWI fly ash is considered as hazardous waste and must be solidifled. The effect of solidifying the MSWI fly ash by cement was studied, and it is indicated that the heavy metals can be well immobilized if the mass fraction of the fly ash is appropriate. The heavy metals were immobilized within cement hydration products through either physical fixation, substhtaion, deposition or adsorption mechanisms.     

空气分级与空气重介流化床分选联合工艺研究

分析了固体颗粒在气-固流化床中的受力情况和运动方程，通过理论分析和实验得出了空气重介流化床分选入料的适宜粒级。讨论了空气重介流化床分选对入料粒度上下限的控制方法和存在问题，介绍了潮湿原煤空气分级新方法。试验表明，空气分级对潮湿原煤颗粒表面的煤粉有“清洗”作用，脱粉效果好，粗粒产物中含粉率仅为0.2%。这对控制入料粉量，稳定流化床密度和减少介质净化非常有利；空气分级还有分选作用，就试验煤种而言，其细粒级产物灰分比原煤中同粒级灰分降低1.7个百分点，比原煤灰分降低7.5个百分点，空气分级和空气重价流化床分选结合，可优化干法选煤工艺，降低工程投资和分选成本50%以上。     

Activation of rejected fly ash using flue gas desulphurization (FGD) sludge

Low-grade fly ash (rejected fly ash, rFA), a significant portion of the pulverized fuel ash (PFA) produced from coal-fired power plants and rejected from the ash classifying process, remains unused due to its high carbon content and large particle size (>45 μm). But it is thought that the rejected ash may have potential uses in chemical stabilization solidification (S/S) processes which need relatively lower strengths and a lower chemical reactivity. Flue Gas Desulphurisation (FGD) sludge is a by-product of air pollution control equipment in coal fired power plants whose chemical composition is mainly gypsum. As there is no effective usage of both of these two materials, it is of interest to research on the possible activation of rFA using FGD. This paper presents experimental results of a study on the properties of rFA activated by the FGD in rFA-cement pastes. Different percentages of FGD were added into the mix to study the effects of the FGD on the reaction of the rFA blended cement pastes. The results show that FGD takes effect as an activator only at late curing ages. Adding Ca(OH)₂ enhances the effect of FGD on activating the hydration of rFA. Also, 10% FGD by weight of rFA is the optimal addition in the rFA-cement pastes. The results of the compressive strength measurements correlate well with the porosity results. QIAO Xiu-chen : Born in 1973 Funded by the Research Grants Council of Hong Kong (Project No. PolyU 5056/00E)     

物理法和化学法对粉煤灰吸附活性的激发

为提高粉煤灰的吸附脱硫活性,本研究利用物理研磨和化学水热化合反应对粉煤灰进行了激发.结果表明:物理激发和化学激发都能不同程度地提高粉煤灰的吸附活性,但化学激发的效果更好;利用化学水热化合反应,在反应温度为90℃、反应时间为12 h、灰钙比为5、水固比为15时,粉煤灰的吸附活性提高最大.     

钢渣粉煤灰活化方法研究

研究了激发剂活化,热力激活,改变钢渣与粉煤灰的化学组成与物相结构等三种钢渣与粉煤灰的预处理活化方法,并且比较了这三种活化方法的优缺点。     

粉煤灰中的含钙矿物及其影响

含钙矿物是粉煤灰中重要的矿物成分,其含量变化会使粉煤灰性质与使用性能发生比较大的变化。总结分析了粉煤灰中含钙矿物的形成过程与存在形态,重点分析了含钙矿物对粉煤灰性能及其应用的影响。结果显示粉煤灰中SO3与CaO含量存在一定线性关系,含钙矿物增加会引起粉煤灰颗粒形貌、硅酸盐离子聚合度等发生变化,提高粉煤灰火山灰活性,但也会引起粉煤灰使用过程中体积稳定性不良,对粉煤灰在水泥混凝土中应用产生不利影响,若合理利用将会使得含钙矿物成为粉煤灰利用的有利因素。     

Properties and mechanism of CFBC fly ash-cement based stabilizers for lake sludge

Circulating fluidized bed combustion(CFBC) fly ash was mixed with cement or lime at a different ratio as a stabilizer to stabilize lake sludge.In order to understand the influences of stabilizers on the lake sludge properties,tests unconfined compressive strength,water stability and SEM observation were performed.The experimental results show that with the increase of the curing time,the strength of all the stabilized specimens increase,especially the samples containing cement.The strength of the specimens is decreased with the increasing of the CFBC fly ash/cement ratio,the optimum ratio between CFBC fly ash and cement is 2:3.The water stability of CFBC fly ash-cement based stabilizers is higher than those of cement and lime.Moreover,the lake sludge stabilization mechanism of CFBC fly ash-cement based stabilizers includes gelation and filling of the hydration products,i e,C-S-H gel and the AFt crystal,which act as benders to solidify those particles together and fill in the packing void of the aggregates.     

利用热等离子体熔融垃圾焚烧飞灰

为了评价垃圾焚烧飞灰的热等离子体熔融处理效果, 研究SiO2和CaO对重金属固化效果和重金属毒性浸出特性的影响. 在飞灰中添加一定比例的SiO2和CaO, 配置成不同的配灰样品, 利用纯氩热等离子体在1 400～1 500 ℃下, 对飞灰及配灰进行熔融玻璃化的实验研究, 分别利用X射线能量色散谱仪(EDX)、场发射扫描电子显微镜(FSEM)、X射线衍射仪(XRD)和毒性浸出方法(TCLP)分析飞灰和熔渣的化学组成、微观结构、晶相组成和重金属毒性浸出特性. 结果表明, 热等离子体熔融所得熔渣为无定形的玻璃体, 重金属浸出质量浓度均远低于毒性标准. SiO2和CaO的添加都可以改善重金属固化效果, CaO比SiO2对Cu、Zn、Cd和Pb挥发的抑制效果更好. SiO2的添加可以改善熔渣中重金属的浸出特性, 而CaO的作用与之相反.